A new study suggests chronic sleep deprivation during infancy and early childhood may increase the risk for obesity by age 7.

“Our study found convincing evidence that getting less than recommended amounts of sleep across early childhood is an independent and strong risk factor for obesity,” Dr. Elsie Taveras, chief of General Pediatrics at MassGeneral Hospital for Children and lead author of the study, said in a press release.

The study, which was published in Pediatrics, analyzed data from Project Viva, a long-term investigation that looks at how environmental factors and lifestyle choices of mothers impacts health of children before birth and in early life. The information was gathered from in-person interviews with mothers and their children at around 6 months, 3 years and 7 years old and from questionnaires completed when the children were 1, 2, 4, 5 and 6 years old.

Mothers were asked to answer questions about their children’s sleeping habits, such as the number of hours the child slept at night and during the day. The researchers took height and weight measurements of the children, as well as measured their total body fat, abdominal fat, lean body mass and waist and hip circumference.

Insufficient sleep was defined as less than 12 hours per day from age 6 months to 2-years old, less than 10 hours a day for children ages 3 and 4, and less than 9 hours a day for children ages 5 to 7. Children were assigned a sleep score covering each of these time periods – from 0 for children with the highest level of sleep deprivation to 13, which was the ideal score for sleep.